Reports of the political death of Sir Menzies Campbell and the Liberal Democrats are both premature and exaggerated, although they have certainly had a rough few months, sagging in the polls and dismissed as irrelevant by much of the media.

And Sir Menzies will find scant comfort in the latest conference poll by Populus for The Times , showing that more than three fifths of the public and two thirds of Lib Dem voters think that if the party is to stand any chance of making an impact he should be replaced by “a younger and more charismatic leader” (for more details see www.populus.co.uk).

However, three in ten (31 per cent) believe that the party has a good team of leaders, only slightly fewer than the Tories, although much lower than in 2004-05. Moreover, nearly half the public think that the party is united and is honest and principled (at 46 per cent, up five points on a year ago).

There is no serious likelihood that Sir Menzies will go in the short term, and he is anyway not the party’s main problem. In 2001 and 2005 the Lib Dems were helped by the unpopularity of both other main parties and by the Iraq War. But Iraq is no longer so important electorally and the Tories and Labour have both been boosted by the election of more popular new leaders.

The Lib Dems consequently face the familiar dilemma of struggling to gain attention. Two thirds of voters, including two fifths of their own supporters, think that they are basically a protest vote party and that, although decent people, their policies probably don’t really add up.

Frustratingly for the party leadership, this comes when the Lib Dems’ policies on many issues, notably tax, social security and climate change, are worked out better than they were before the 2005 election. They cannot be accused of being wishy-washy and we will hear detailed and ambitious policy proposals this week from the likes of Vince Cable, Chris Huhne, Nick Clegg and David Laws.

The Populus poll suggests that at least the high profile being given to a carbon-neutral policy may be resonating with voters, as half of them agree with the Liberal Democrat approach of raising taxes on environmentally damaging behaviour and using the money to cut direct taxes. But voters always tend to get greener in general than when faced with specific painful choices.

Recent polls have put the party in the 15 to 18 per cent range, down from 23 per cent at the 2005 election. If there were a uniform swing across the country, this might leave the Lib Dems with only about 30 MPs, half their current total.

That is seen as far too pessimistic by party strategists, and they are partly correct because of the more ruthless focus on target seats. First, the party has, with the exception of 2003-05, often been at this level in national polls in mid-term and then gained during election campaigns, by between one and four points, again with 2005 an exception. Secondly, incumbent Lib Dem MPs are often hard to shift and, for a time, can resist national tides. Thirdly, tactical voting has previously helped Lib Dems in target seats. Despite disappointing overall results in the May elections, the party did well in some key Lib Dem-Tory marginals, such as Taunton and Westmoreland, and in seats they hope to win from Labour in big cities and the North, such as Hull North and Liverpool Wavertree.

Such targeting does, however, often mitigate but not halt an adverse national swing, as happened in 1970 and 1979, and many Lib Dem seats in the South are vulnerable to the Tories.

For the first time in a preelection party conference for 16 years, the Lib Dems face a two-party squeeze. They are on the defensive electorally, hoping to minimise losses rather than to advance. Nationally, that requires an effective offensive strategy to gain attention.

Times Recommends

• Sarah Brown says 'no thanks' to veal at G8 - twice
• Stockton-on-Tees is obesity capital of Britain
• Stores blame poor sales on Murray factor